1. Field of the Invention
The present invention relates to a method of manufacturing an opto-electric hybrid module including an optical waveguide and an electric circuit mounted with an optical element, and to an opto-electric hybrid module manufactured by the method.
2. Description of the Related Art
As shown in FIG. 7, an exemplary method of manufacturing an opto-electric hybrid module is such that an electric circuit board 80 and an optical waveguide unit 70 are separately prepared and bonded together by an adhesive agent 90, and a light emitting element 23 and a light receiving element 33 are respectively mounted in association with opposite ends of the optical waveguide unit 70 on the electric circuit board 80 (see, for example, JP-A-2000-199827). The electric circuit board 80 includes an electric circuit 82 provided on one surface (an upper surface in FIG. 7) of a stainless steel plate 81 with an insulating layer (not shown) in-between and having mount pads 82a on which the light emitting element 23 and the light receiving element 33 are mounted. The optical waveguide unit 70 includes an over-cladding layer 73, a core 72 and an under-cladding layer 71 provided in this order on the other surface (a lower surface in FIG. 7) of the stainless steel plate 81. The optical waveguide unit 70 has surfaces inclined at 45 degrees with respect to its optical axis at its opposite ends. End faces of the core 72 located in the inclined surfaces respectively serve as light reflection surfaces 72a, 72b. The opto-electric hybrid module has a light transmission through-hole 81a formed in the electric circuit board 80 in association with the light emitting element 23 so that light (optical signal) L emitted from the light emitting element 23 can be inputted into one end portion of the core 72 adjacent to the light emitting element 23. Further, the opto-electric hybrid module has a light transmission through-hole 81b formed in the electric circuit board 80 in association with the light receiving element 33 so that light L emitted from the light emitting element 23, then passing through the core of the optical waveguide unit 70 and reflected on the light reflection surface 72b adjacent to the light receiving element 33 can be received by the light receiving element 33. In FIG. 7, a reference character 23a denotes a bump (electrode) of the light emitting element 23, and a reference character 33a denotes a bump (electrode) of the light receiving element 33.
The light L is transmitted in the following manner in the opto-electric hybrid module. First, the light L is outputted downward from the light emitting element 23. The light L passes through one end portion (a left end portion in FIG. 7) of the over-cladding layer 73 of the optical waveguide unit 70 to be inputted into the one end portion of the core 72. Then, the light L is reflected on the light reflection surface 72a at the one end of the core 72 to be transmitted axially through the core 72. The light L passes through the core 72 to the other end (a right end in FIG. 7) of the core 72. Then, the light L is reflected upward on the light reflection surface 72b at the other end to be outputted through the over-cladding layer 73 and received by the light receiving element 33.